1. Field of the Invention
The invention relates to apparatus in a photographic camera for detecting that a camera user's finger (or other portion of the user's hand) may be in front of the taking lens.
2. Description of the Prior Art
As photographic cameras get smaller in size, it becomes more likely that a camera user may inadvertently locate a finger in front of the taking lens before the user depresses the shutter release to take a picture. Should the user take a picture with a finger over the lens, the picture will of course be ruined.
A solution to this problem, as shown in U.S. Pat. No. 3,878,548, granted Apr. 15, 1975, is a mechanism for alerting the camera user before the user takes a picture that the user's finger is located in front of the taking lens. In the patent, a lens cover is manually slidable along an elongate opening in the camera face between a closed position, covering a lens opening, and an opened position, behind the camera face. When the lens cover is in the opened position, the only portion of it that is accessible to the camera user is a push tab, which projects from the elongate opening at a location proximate the lens opening (and in an alternate embodiment, extends around the lens opening). If a camera user's finger is pressed against the push tab, with the lens cover in the opened position, the cover is shown to swing inwardly from behind the camera face about a secured end of the cover remote from the push tab. Such a change of positon of the lens cover causes it to move a warning flag into the viewfinder, which alerts the camera user before the user takes a picture that the user's finger is located in front of the taking lens.
While the mechanism disclosed in the '548 patent may perform satisfactorily, it appears to have certain limitations. For example, when a finger is inadvertently placed over the taking lens at different angles, the lens cover must always undergo substantially the same change of position to alert the camera user that the user's finger is blocking the lens. As disclosed, the lens cover is supported for pivotal movement only about one axis, and therefore is restricted to the same change of position for alerting the camera user, regardless of the angle of a finger over the taking lens. Restricting the lens cover, under these circumstances, to only one change of position limits its sensitivity as a finger over the lens sensor, hastens its wear, and may make it susceptible to jamming.